1. Field of the Invention
The present invention relates to a building change detection apparatus or the like that detects a change in a feature, particularly, a building, on a map.
2. Description of the Related Art
Methods of detecting a change in a building (structure) on a map include a method of detecting changes in buildings on a map by projecting the map on an aerial photograph and visually comparing the buildings on the map with buildings on the aerial photograph one by one. However, this scheme brings about problems of needing a lot of works and cost due to visual examination of all changes in buildings on a map, and causing manual-work originated mis-detection.
A change in a building on a map indicates a change originated from disappearance of a structure or new building of a structure. Disappearance of a structure means that a structure disappears to leave a vacant land. New building of a structure means that a new structure is added on a vacant land.
In view of such circumstances, there has been proposed a building change detection method using an aerial photograph, a satellite image or the like as described in Unexamined Japanese Patent Application KOKAI Publication No. 2002-63580. Unexamined Japanese Patent Application KOKAI Publication No. 2002-63580 describes an image matching method of automatically searching an image for a structure which matches with an indefinite-shaped window created from the shape of a house on a map using two or more kinds of images of the same area picked up by aerial photographing or satellite imaging, and notifying disappearance of a structure when there is no structure matching with the indefinite-shaped window.
Other techniques of determining a change in structure or the like from new and old image data or laser data are described in Unexamined Japanese Patent Application KOKAI Publication No. 2004-117245, Unexamined Japanese Patent Application KOKAI Publication No. 2007-3244 and Unexamined Japanese Patent Application KOKAI Publication No. 2007-34808. Further, Unexamined Japanese Patent Application KOKAI Publication No. 2004-198530 and Unexamined Japanese Patent Application KOKAI Publication No. 2005-234603 describe a technique of collating a map with image data to determine a change in a feature, such as new building of a structure, on the map.
Unexamined Japanese Patent Application KOKAI Publication No. H03-167678 describes a method of acquiring three-dimensional numerical data from a stereo image.
The specification of Japanese Patent Application No. 2007-145971 filed by the same applicant as the present invention describes the invention that extracts height data of a feature on the ground from a plurality of photographed images of the ground by stereo matching process to detect disappearance of a structure and new building thereof based on a change in height.
In detecting disappearance of a building and new building thereof based on a change in height of a feature acquired from image data simply by using the aforementioned related art, the following erroneous detection may occur due to the influences of a feature other than a building, such as a tree, road, river or lake.
For example, growing, pruning, cutting or the like of a tree changes the height thereof. Therefore, there is a possibility that the changed portion of the tree is erroneously detected as a changed portion of a building. When a tree at a predetermined location grows and gets taller, for example, such may be erroneously detected that a building has been newly built at the location. When a tree is cut to get shorter, such may be erroneously detected that a building has disappeared.
Vehicles run on a road, so that if an image is photographed while a large vehicle, for example, is running, it may be erroneously detected that a building has been newly built at the location. When a vehicle which has been present on a road before does not exist at the time of next shooting, on the other hand, it may be erroneously detected that a building has disappeared.
In addition, a river, lake or the like greatly changes its height from the ground due to a weather, tide or the like, which is a large factor in erroneous detection of a change in a building.